In previously designed twist selector grips intended for mounting on pedal cycle handlebars, in which the selector grip pulls on a tension means against a spring installed in the gear mechanism, two principles are used.
In one prior design, shown in European patent document EP 0 423 779 A1, a cable is wound without slippage on a spool slid over the pedal cycle handlebar. By using the pedal cycle handlebar, however, a minimum diameter, and thus a minimum circumference of the spool, is determined. Because the cable is wound on this circumference, relatively great longitudinal movements of the cable occur as a result of even small rotary movements of the spool, which works against the desire for precise selection.
In another prior design, such as shown in U.S. Pat. No. 5,102,372 and European patent document EP 0 575 560 A1, a cable fastened to a non-rotatable part of the selector grip is laid in a loop around a rotatable cam. By turning this cam, the cable loop is expanded and a relatively slight linear movement is achieved through rather large rotary movements. This solution has the disadvantage of the large wrap angle of the cable around the cam, which brings about relatively high friction between the cam and the cable.